Development of a Selective Adsorbing Material for Binding of Pyrrolizidine Alkaloids in Herbal Extracts, Based on Molecular Group Imprinting

Planta Medica ◽  
2019 ◽  
Vol 85 (13) ◽  
pp. 1107-1113 ◽  
Author(s):  
Thomas Kopp ◽  
Mona Abdel-Tawab ◽  
Martin Khoeiklang ◽  
Boris Mizaikoff
Keyword(s):  
Pyrrolizidine Alkaloids ◽  
Binding Capacity ◽  
Specific Binding ◽  
Pyrrolizidine Alkaloid ◽  
Daily Intake ◽  
Chelidonium Majus ◽  
Molecular Imprinted Polymers ◽  
Binding Characteristics ◽  
Molecular Group ◽  
Plant Constituents

AbstractPyrrolizidine alkaloids are secondary plant constituents that became a subject of public concern because of their hepatotoxic, pneumotoxic, genotoxic, and cytotoxic effects. Due to disregardful harvesting and/or contamination with pyrrolizidine alkaloid-containing plants, there is a high risk of ingesting these substances with plant extracts or natural products. The limit for the daily intake was set to 0.007 µg/kg body weight. If contained in an extract, cleanup methods may help to minimize the pyrrolizidine alkaloid concentration. For this purpose, a material for depleting pyrrolizidine alkaloids in herbal preparations was developed based on the approach of molecular imprinting using monocrotaline. Molecular imprinted polymers are substances with specific binding characteristics, depending on the template used for imprinting. By means of group imprinting, only one molecule is used for creating selective cavities for many molecular pyrrolizidine alkaloid variations. Design of Experiment was used for the development using a 25 screening plan resulting in 64 polymers (32 MIPs/32 NIPs). Rebinding trials revealed that the developed material can compete with common cation exchangers and is more suitable for depleting pyrrolizidine alkaloids than C18- material. Matrix trials using an extract from Chelidonium majus show that there is sufficient binding capacity for pyrrolizidine alkaloids (80%), but the material is lacking in selectivity towards pyrrolizidine alkaloids in the presence of other alkaloids with similar functional groups such as berberine, chelidonine, and coptisine. Beyond this interaction, the selectivity could be proven for other structurally different compounds on the example of chelidonic acid.

scholarly journals Core Imprinting: An Alternative and Economic Approach for Depleting Pyrrolizidine Alkaloids in Herbal Extracts

2020 ◽  
Vol 7 (01) ◽  
pp. e26-e33 ◽  
Author(s):  
Thomas Kopp ◽  
Mona Abdel-Tawab ◽  
Boris Mizaikoff
Keyword(s):  
Pyrrolizidine Alkaloids ◽  
Pyrrolizidine Alkaloid ◽  
Daily Intake ◽  
Mentha Piperita ◽  
Molecular Imprinted Polymer ◽  
Chelidonium Majus ◽  
Imprinted Polymer ◽  
Structural Element ◽  
Federal Institute ◽  
Marker Compounds

AbstractDue to the high toxicity of pyrrolizidine alkaloids, in 2011, the German Federal Institute of Risk Assessment recommended that their daily intake limit should be no more than 0.007 µg/kg body weight. The risk of ingesting these substances in herbal preparations, either from their inherent presence in plants or through contamination with pyrrolizidine alkaloid-containing weeds, should not be underestimated. A promising molecular imprinted polymer was developed previously to minimise exposure to these compounds. Due to the high costs of the template and the risk of template bleeding, an alternative and more economic pyrrolizidine alkaloid depleting strategy is still required. Core imprinting, which focuses on the most important structural element in the target molecule, was investigated using triethylamine and tetraethylammonium as easily available and cheap alternative templates. The suitability of core imprinting was demonstrated using a pyrrolizidine alkaloid standard solution if an excess of an alternative template compared to monocrotaline was used for imprinting. Matrix trials in pyrrolizidine alkaloid-spiked Mentha piperita, Chelidonium majus, Glycyrrhiza glabra, and Matricaria chamomilla extracts containing Echium vulgare revealed better pyrrolizidine alkaloid binding than demonstrated for the original molecular imprinted polymer. Echimidine and echimidine-N-oxide were depleted in the range of 31.8–70.0 and 26.1–45.1%, respectively. However, solvent-dependent differences in pyrrolizidine alkaloid binding and inherent plant analytical marker compounds were observed. Hence, binding of analytical marker compounds was better minimised in methanolic than in ethanolic extracts. The present study reveals core imprinting to be an economic alternative approach for depleting pyrrolizidine alkaloids in plant extracts.

SPECIFIC BINDING OF THYROID-STIMULATING HORMONE BY HUMAN SERUM GLOBULINS

1981 ◽  
Vol 88 (3) ◽  
pp. 339-349 ◽  
Author(s):  
J. BÍRÓ
Keyword(s):  
Binding Sites ◽  
Binding Capacity ◽  
Specific Binding ◽  
Negative Control Group ◽  
Paper Electrophoresis ◽  
Negative Control ◽  
Thyroid Stimulating Hormone ◽  
Human Thyroid ◽  
Control Group ◽  
Binding Characteristics

Globulin preparations (41) from patients with Graves's disease (positive to thyroid stimulating immunoglobulins; TSI) and 12 from healthy persons (TSI-negative) were tested for their specific thyrotrophin (TSH)-binding properties. Globulins from both groups possessed binding sites for 131I-labelled TSH. The mean dissociation constant (Kd) was 6·8 pmol/l per mg globulin and the maximum specific binding (Bmax) was 3·0 pmol/mg globulin per 1 for the TSI-negative control group. Twenty-four (58·5%) globulin preparations from the TSI-positive group had similar TSH-binding characteristics with mean Kd of 7·2 pmol/l per mg globulin and Bmax of 3·6 pmol/mg globulin per 1 (A-type binding) but the remaining 17 (41·5%) bound TSH in a different fashion with Kd of 71·5 pmol/l per mg globulin and Bmax of 13·6 pmol/mg globulin per 1 (B-type binding). Both types of specific TSH binding reached the maximal level within 1 h of incubation and had an optimum pH of 7–8. There was a linear correlation between the amount of bound TSH and the globulin content of the samples. Both types of binding were reversible by the addition of an excess of TSH and gonadotrophins, ACTH, prolactin and insulin competed with TSH for the binding sites only when in relatively high concentrations. The binding sites were associated with macromolecules; they emerged with the void volume after chromatography on Sephadex G-200 and migrated with immunoglobulin G (IgG) on paper electrophoresis. The binding capacity of the globulin preparations could be decreased by preincubation with antiserum to human IgG or with human thyroid membranes.

Immunocytochemical verification of the insulin receptor's specificity in the nuclear envelope of Tetrahymena. Comparison with receptors of the plasma membrane

1994 ◽  
Vol 14 (1) ◽  
pp. 25-31 ◽  
Author(s):  
G. Csaba ◽  
Hargita Hegyesi
Keyword(s):  
Monoclonal Antibodies ◽  
Plasma Membrane ◽  
Nuclear Envelope ◽  
Hormone Receptors ◽  
Binding Capacity ◽  
Specific Binding ◽  
Antibody Technique ◽  
Binding Characteristics ◽  
Immunocytochemical Method ◽  
Higher Rank

The unicellular Tetrahymena possess hormone receptors in the nuclear envelope similarly to higher rank animals. These receptors bind insulin and their specificity is detectable by monoclonal antibodies developed to insulin. The hormonal (insulin) pretreatment (imprinting) of the cell did not alter the binding capacity of the nuclear membrane, demonstrated by antibody-technique. The specific binding characteristics of the plasma membrane was demonstrated and this was significantly increased following imprinting. In the nucleus of Tetrahymena presence of insulin was not detected by immunocytochemical method.

Distribution of prostaglandin E2 and prostaglandin F2α receptors in human myometrium

1981 ◽  
Vol 98 (3) ◽  
pp. 446-450 ◽  
Author(s):  
Th. Bauknecht ◽  
B. Krahe ◽  
U. Rechenbach ◽  
H. P. Zahradnik ◽  
M. Breckwoldt
Keyword(s):  
Binding Capacity ◽  
Specific Binding ◽  
Prostaglandin F2α ◽  
Cervical Region ◽  
Human Myometrium ◽  
Binding Characteristics ◽  
Receptor Kinetics ◽  
Fold Reduction ◽  
Pre Treatment ◽  
Post Menopausal

Abstract. Human myometrium was studied for specific binding of PGE2 and PGF2α. PGF2α-binding was almost undetectable, but specific binding sites for PGE2 with high affinity (KD = 2.7 ± 0.4 × 10−9 m were demonstrated. The binding capacity for PGE2 exhibited a topically different distribution pattern with the highest values in the central parts and low to undetectable levels in the cervical region. Binding characteristics were analyzed by receptor kinetics, revealing a homogenous receptor population. Binding capacity in uteri obtained from post-menopausal women was of the order of 900–940 fmol/mg protein. Oestrogen pre-treatment and pregnancy were associated with a 3-fold reduction of the PGE2-binding capacity.

In-vitro binding of gonadotrophin to fish ovary

1986 ◽  
Vol 111 (3) ◽  
pp. 407-413 ◽  
Author(s):  
Md. Jamal Uddin ◽  
S. Bhattacharya
Keyword(s):  
Plasma Membranes ◽  
Binding Capacity ◽  
Specific Binding ◽  
Ovarian Tissue ◽  
Silver Carp ◽  
Binding Studies ◽  
Binding Characteristics ◽  
Physiological Importance ◽  
Plot Analysis

ABSTRACT Binding of piscine and mammalian gonadotrophin to plasma membranes from the ovaries of a fish, the murrel (Channa punctatus), clearly suggests that the fish ovary possesses distinct and specific binding sites for both piscine and mammalian gonadotrophins. Maximum specific binding of 125I-labelled human chorionic gonadotrophin (125I-hCG) and 125I-labelled silver carp gonadotrophin (125I-scG) was obtained at 30 °C and pH 7·5 during 2 h of incubation. In competitive binding studies, binding of radiolabelled scG was effectively inhibited by piscine gonadotrophins while LH and hCG had less effect and FSH showed no inhibition. By using plasma membrane preparations from kidney, skeletal muscle, brain and ovary it could be shown that specific binding of radiolabelled gonadotrophins was restricted to ovarian tissue. Binding characteristics of both 125I-scG and 125I-hCG to a preparation of murrel ovarian plasma membranes showed saturability with high affinity and low capacity. Scatchard plot analysis gave a higher dissociation constant for hCG (Kd = 235 pmol/l) than for scG (Kd= 127 pmol/l). Maximum binding capacity of scG was about twofold higher (6·27 fmol/mg protein) than that of hCG (3·76 fmol/mg protein). An increase in gonadotrophin binding resulted in a greater formation of pregnenolone from cholesterol, indicating functional relevance. At a concentration of 8 mmol/l, Ca2+ markedly inhibited the binding of gonadotrophin. The physiological importance of this inhibition is discussed. J. Endocr. (1986) 111, 407–413

Pyrrolizidine Alkaloid Contamination in Medicinal Plants: Regulatory Requirements and Their Impact on Production and Quality Control of Herbal Medicinal Products

Planta Medica ◽  
2021 ◽  
Author(s):  
Barbara Steinhoff
Keyword(s):  
Pyrrolizidine Alkaloids ◽  
Pyrrolizidine Alkaloid ◽  
Daily Intake ◽  
Herbal Drugs ◽  
Herbal Extracts ◽  
Medicinal Products ◽  
Plant Materials ◽  
Herbal Medicinal Products ◽  
Code Of Practice ◽  
Herbal Medicinal

AbstractAgainst the background of potential contamination of medicinal plant materials with pyrrolizidine alkaloids caused by weeds, suppliers of herbal drugs and manufacturers of herbal medicinal products have taken action by establishing a Code of Practice by monitoring potential contamination and by collection of data. In August 2020, the Herbal Medicinal Products Committee, in its new draft public statement, proposed a daily intake of 1.0 µg of pyrrolizidine alkaloids per day for adults in general, also including contaminations of herbal medicinal products. Over the past years, the results of data collections showed a remarkable reduction of the pyrrolizidine alkaloid burden in herbal drugs and herbal extracts. Meanwhile, a stable situation has been achieved for herbal drugs, while further improvement can be observed for herbal extracts. The results indicate that the implemented measures have been efficient and contribute to a continuous and sustainable reduction of pyrrolizidine alkaloid contamination. A permanent limit of 1.0 µg of pyrrolizidine alkaloids per day is considered appropriate to guarantee sufficient availability of batches used for the production of herbal medicinal products. The new Ph.Eur. general chapter 2.8.26 describes, as an example, an analytical procedure suitable for the determination of target pyrrolizidine alkaloids.

Human chorionic gonadotropin binding sites in the human endometrium

1993 ◽  
Vol 129 (1) ◽  
pp. 15-19 ◽  
Author(s):  
S Bhattacharya ◽  
J Banerjee ◽  
S Sen ◽  
PR Manna
Keyword(s):  
Metal Ions ◽  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Binding Sites ◽  
Binding Capacity ◽  
Specific Binding ◽  
Human Endometrium ◽  
Binding Characteristics ◽  
High Affinity ◽  
Specific Binding Sites

The existence of high-affinity and low-capacity specific binding sites for luteinizing hormone (LH)/human chorionic gonadotropin (hCG) has been reported in porcine, rabbit and rat uteri. We have identified hCG binding sites in the human endometrium collected from 35–42-year-old ovulatory and anovulatory women. The binding characteristics of hCG to endometrial tissue preparations from ovulatory and anovulatory women showed saturability with high affinity and low capacity. Scatchard plot analysis showed the dissociation constant of specific binding sites in the ovulatory women to be 3.5 × 10−10 mol/l and in anovulatory women to be 3.1 × 10−10 mol/l. The maximum binding capacity varied considerably between ovulatory (3.85 nmol/kg protein) and anovulatory (6.12 nmol/kg protein) endometrium. Among the divalent metal ions tested (Zn2+, Mg2+, Mn2+, Ca2+—4 mol/l), Zn2+ effected a remarkable increase in [125I]hCG binding to the endometrium (p<0.005) whereas Mn2+ showed a marginal increase and other metal ions did not have any effect. Data obtained with human endometrium indicate an influence of the functional state of the ovary on [125I]hCG binding to endometrium.

Fasting alters somatostatin binding to liver membranes of rainbow trout (Oncorhynchus mykiss)

1996 ◽  
Vol 150 (2) ◽  
pp. 179-186 ◽  
Author(s):  
M J Pesek ◽  
M A Sheridan
Keyword(s):  
Rainbow Trout ◽  
Binding Sites ◽  
Binding Capacity ◽  
Specific Binding ◽  
Scatchard Analysis ◽  
Binding Characteristics ◽  
High Affinity ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
C Terminus ◽  
Liver Membranes

Abstract Somatostatins are a diverse family of peptides that influence various aspects of animal growth, development, and metabolism. Recent work in our laboratory has shown that somatostatins stimulate hepatic lipolysis in rainbow trout. In this study we characterized somatostatin-binding sites in trout hepatic membrane preparations. We also examined changes in binding characteristics brought about by food deprivation. Binding of [Tyr11]-somatostatin-14 (SS-14) was saturable, reversible, and time- and temperature-dependent. Under optimal conditions, [Tyr11]-SS-14 specific binding averaged 5·7 ± 0·3%. While SS-14 and SS-28 (an N-terminally extended form of SS-14 and derived from the same gene as SS-14) displaced [Tyr11]-SS-14 specific binding (ED50 values of approximately 50 nm and 100 nm respectively), salmon SS-25 (containing [Tyr7,Gly10]-SS-14 at its C terminus and presumably derived from a gene different from that giving rise to SS-14/SS-28), except at pharmacological concentrations, did not. Significant specific binding was also detected in brain, esophagus, stomach, upper and lower intestine, pancreas, and adipose tissue. Scatchard analysis suggested the existence of two classes of hepatic somatostatin-binding sites: a high-affinity site with a Kd of 23 nm and Bmax of 1·4 pmol/mg protein and a low-affinity site with a Kd of 379 nm and Bmax of 4·9 pmol/mg protein. Fasting resulted in reduced growth and elevated plasma levels of SS-14 compared with fed animals. SS-14 binding capacity of the high-affinity class in liver membranes isolated from fasted fish increased by 120% over that from fed counter-parts. No difference in Kd for the high-affinity binding class or in either Kd or Bmax of the low-affinity class was noted between fasted and fed animals. These data support the role of the liver as a target of somatostatin and suggest that fasting enhances hepatic sensitivity to SS-14 binding. Journal of Endocrinology (1996) 150, 179–186

Concanavalin A-induced Aggregation of Human Blood Platelets

1975 ◽  
Vol 33 (02) ◽  
pp. 354-360 ◽  
Author(s):  
Heinrich Patscheke ◽  
Reinhard Brossmer
Keyword(s):  
Concanavalin A ◽  
Binding Capacity ◽  
Specific Binding ◽  
Blood Platelets ◽  
Residual Effect ◽  
Independent Effect ◽  
Con A ◽  
Experimental Conditions ◽  
Main Effect ◽  
Induced Aggregation

SummaryConcanavalin A (CON A) causes platelets to aggregate. A Ca++-independent effect of CON A could be separated from a main effect which depends on Ca++. The main effect probably is a consequence of the CON A-induced platelet release reaction and therefore is platelet-specific. The weak residual effect observed in the presence of Na2EDTA may be due to a similar mechanism as has been demonstrated for CON A-induced aggregations of several other normal and malignant transformed animal cells.Na2EDTA did not inhibit the carbohydrate-specific binding capacity of CON A. Therefore, Na2EDTA appears not to demineralize the CON A molecules under these experimental conditions.α-methyl-D-glucoside inhibits the Ca++-independent as well as the Ca++-dependent effect of CON A.Pretreatment by neuraminidase stimulated the platelet aggregation induced by CON A. It is possible that removal of terminal sialic acid residues makes additional receptors accessible for the binding of CON A.

scholarly journals Production of Recombinant Monoclonal Antibodies in the Egg White of Gene-Targeted Transgenic Chickens

Genes ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 38
Author(s):  
Takehiro Mukae ◽  
Sho Okumura ◽  
Takuma Watanobe ◽  
Kyoko Yoshii ◽  
Takahiro Tagami ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Binding Capacity ◽  
Specific Binding ◽  
Egg White ◽  
Peptide Sequence ◽  
Efficient Production ◽  
Antigen Binding ◽  
Transgenic Chicken ◽  
Bioreactor System ◽  
Transgenic Chickens

Increased commercial demand for monoclonal antibodies (mAbs) has resulted in the urgent need to establish efficient production systems. We previously developed a transgenic chicken bioreactor system that effectively produced human cytokines in egg whites using genome-edited transgenic chickens. Here, we describe the application of this system to mAb production. The genes encoding the heavy and light chains of humanized anti-HER2 mAb, linked by a 2A peptide sequence, were integrated into the chicken ovalbumin gene locus using a CRISPR/Cas9 protocol. The knock-in hens produced a fully assembled humanized mAb in their eggs. The mAb expression level in the egg white was 1.4–1.9 mg/mL, as determined by ELISA. Furthermore, the antigen binding affinity of the anti-HER2 mAb obtained was estimated to be equal to that of the therapeutic anti-HER2 mAb (trastuzumab). In addition, antigen-specific binding by the egg white mAb was demonstrated by immunofluorescence against HER2-positive and -negative cells. These results indicate that the chicken bioreactor system can efficiently produce mAbs with antigen binding capacity and can serve as an alternative production system for commercial mAbs.

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